Rooftop air intake unit louver



March 3, 1970 KAUTZ ETAL 3,498,205

ROOFTOP AIR INTAKE UNIT LOUVER I Filed July 26, 1968 INVENTORS EA. KAUTZ3y FA. BREWER lrmmrey a PP WA/DE/PMEUT' United States Patent 3,498,205ROOFTOP AIR INTAKE UNIT LOUVER Franz A. Kautz, Philadelphia, Forrest A.Brewer, Levittown, and Paul P. Vanderneut, Philadelphia, Pa., as-

signors to International Telephone & Telegraph Corporation, New York,N.Y., a corporation of Delaware Filed July 26, 1968, Ser. No. 748,094Int. Cl. F24f 7/02 U.S. C]. 98-37 2 Claims ABSTRACT OF THE DISCLOSUREThe air intake of an air conditioning housing has vertical louvers witha somewhat L-shaped cross-section. At the toe-end tip of the lower lineof this L-shaped cross-section, the louver is bent upward somewhat as aserif might appear at the toe-end tip of a printed letter L. This serifbent on the louver serves three functions: first, it forms a low speedair foil creating a dead air zone where the louver is not wiped by theon-rushing airstream; second, it forms a gutter for catching theraindrops in the airstream; and third, it tends to bend the airstreamand swing it around toward an entrance of an airduct in the housing.

This invention relates to rooftop units having air intake louvers andmore particularly to air conditioning units having louvers on more thanone side.

For any of many reasons, rooftop or other similarly situated unitssometimes have air intakes. For example, engines, air conditioningunits, furnaces, filtration systems, mine shafts, and the like, mustpump fresh air from the atmosphere into an enclosure, such as abuilding. While the exact reason for drawing in air is not too relevant,the following description speaks of a rooftop air-conditioner since itexemplifies the problems involved.

'In general, the prior art has provided air'intakes on only one side ofa housing. If the wind blows over the housing, there is a pressuredifferential with a high pressure building up on the side of the housingwhich is struck by the wind and a low pressure or partial vacuum formingon the opposite side of the housing. Thus, there would be a naturaltendency for fresh air to enter the housing on the high pressure sideand to leave it on the low pressure side-without diversion of the freshair into the housing, as intended. If an air intake is provided on onlyone side of the housing, there is a problem of insuring an adequate flowinto the housing. Sometimes, the single intake is on the low pressureside of the housing and the air naturally wants to flow out of insteadof into the building.

Another problem relates to a separation of rain from the inflowing air.If there is a hard driving storm, the raindrops may be driven throughthe louvers and into the housing with a resulting flooding that maycause equipment failures, hasten the aging of the various components, orrequired rugged weather resistant components.

Accordingly, an object of the invention is to provide new and improvedlouvered air intakes. In this connection, an object is to provide aplurality of air intakes on several sides of a housing to insure a fulland adequate flow of air into each of the intakes regardless ofprevailing wind directions. Here an object is to provide a rooftophousing unit having louvered air intakes which may be located in anyposition on the housing without regard to the direction of prevailingwinds.

Yet another object of the invention is to separate rain and othermoisture droplets from the fresh air pulled through the louveredintakes.

Still another object is to provide an air baffling system 3,498,205Patented Mar. 3, 1970 Ice which permits a mixing of outside and insideair in a predetermined ratio regardless of indoor and outdoor pressuredifferentials.

In keeping with one aspect of the invention, the foregoing and otherobjects are accomplished by providing a housing having vertical louverswith a somewhat L- shaped cross-section. At the toe-end tip of the lowerline of this L-shaped cross-section, the louver is bent upward somewhatas a serif might appear at the toe-end of a printed letter L. This serifbend on the louver serves three functions: first, it forms a low speedair foil creating a dead air zone where the louver is not wiped by theonrushing airstream; second, it forms a gutter for catching theraindrops in the airstream; and third, it tends to bend the airstreamand swing it around toward an entrance of an airduct in the housing.Other parts of the housing are shaped to cooperate with the louvers anddrain away the water caught by the gutter action of the serif tip, andto mix the inside and outside air in the desired ratio.

The above mentioned and other features and objects of this invention andthe manner of obtaining them will become more apparent, and theinvention itself will be best understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanying drawings, in which:

FIG. 1 is a perspective view of an exemplary building having a rooftopunit constructed as taught herein;

FIG. 2 is a cross-sectional view of the louver showing the L-shape withthe serif tip bend at the toe-end of the L;

FIG. 3 is a plan view of the air intake portion of the rooftop unit seenin FIG. 1; and

FIG. 4 is a cross-sectional view of the air intake portion taken alongline 44 of FIG. 3.

FIG. 1 shows a rooftop air-conditioner as an example of one kind of aunit which might use the invention. In greater detail, anair-conditioned building 20 has a housing 21 mounted on its roof. Oneend 22 of the housing 21 provides for the intake of air, and the otherend '24 provides for the exhaust of the air into the building 20.

While it travels through the housing 21, the air is conditioned in anyknown manner.

On each of its sides, the intake end 22 of the housing 21 includes anopen area having a pair of intake louvers 25, 26 thereinthe louver 26being hidden from view in FIG. 1. The output end 24 of housing 21includes a number of ducts 27 (appearing in a broken section of theroof) for carrying the conditioned air into the various zones of thebuilding. This air returns to the housing 21 pressure there. The wind issweeping over the side having the louver 26 and is building a slightvacuum there.

The invention teaches that the louvers at 25 and 26 should be made inthe form of a series of vertical slats having a generally L shapedcross-section (FIG. 2). In greater detail, one side 40 of the slat 41represents the upright arm of the L, and it is placed facing into thestream of air 30, thereby splitting it into a plurality of individualairstreams 42, 43. The lower arm 44 of the L forms the other side of theslat 41, positioned at the exit side of the louver where the splitairstreams 42, 43 merge to reform single airstream 45. At the toe-endtip 46 of the louver arm of the L, the side 44 is bent to form a side orgutter positioned much as a serif is positioned at the lower rightcorner of an Lprinted as a capital letter. Hence, for convenience ofexpression this part 46 of the louver is hereinafter called the seriftip at the toe-end of the louver slat.

Upon inspection, it should be apparent that the side 44 and the seriftip 46 form a low speed air foil. The airstream 43 flowing over the topside of slat 41 wipes the edges whereas the airstream 42 flowing underthe lower side of slat 41 tends to travel over a more or less straightline, leaving a dead air corner area 49 free of a wiping action. Also,the raindrops and other particles in the airstream 42 are relativelyheavy, and they will tend to turn slower than the gaseous parts of theairstream. Thus, the inertia of these heavy particles causes them tostrike the inner edge of the serif tip 46 in the dead air region 49, andthen to run downwardly under the force of gravity.

The velocity of the airstream represented by the individual arrows48which is impeded by the serif tip is reduced slightly as compared withthe velocity of the unimpeded airstream represented by the individualarrow 50. Also, the unwiped dead air in the space in front of the seriftip 46 tends to be compressed a little and to have a slightly increasedair pressure. These factors combine to bend or deflect the airstream 45as shown by the curving arrows 51. As best seen in FIG. 3, the airstreamis, therefore, directed in an arc flowing into the housing 21. Likewise,the airstream flowing in through louvers 26 is similarly deflected intothe housing 21. Thus, there is no appreciable flow of air from theintake louver on the side having the highest outside atmosphericpressure and across the open area to the intake louver on theside havingthe lowest pressure. While the water particles are primarily trapped inthe gutters formed by the serif tips 46 on the toe-ends of the louvers,some such particles may be carried along by the airstream which does notimpinge upon tip 46--such as is indicated by the arrow 50. When thishappens, the heavier water drops tend to continue in a line, asindicated at 53, to splash against wall baflles 54, 55 and then to rundown the wall. The floor 56 of the open area on the intake end of thehousing 21 is slanted or sloped so that the water striking baffles 54,55 runs off to the outside of the housing.,It has been found that an airintake constructed as described above separates air and water veryefliciently so that almost no free water enters the housing 21.

To provide for the mixing of outside and return air, the open area atthe intake end of the housing 21 is divided into two parts by the floor56. The outside airstreams 30, 45 enter the louvered intake at 25, 26deflect and flow above the floor 56 and through an opening 59 to thehousing 21. The return air 31, from inside of the building 20 flowsinpart 66upwardly and into the space 67 below the floor 56 and then intohousing 21.

The entry into spaces 59 and 67 is controlled by dampers which may beopened or closed in any degree by suitable servo motors (not shown)driven responsive to any environmental sensors. Thus, for example,dampers in opening 59 may be opened relatively widely, and dampers inopening 67 may be opened much less widely to provide an in-housing mixof say 75% outside air and 25% inside air. An exhaust fan drives theremainder 69 of the returning airstream 31 outwardly from the spacebeneath the floor 56 to the atmosphere. Other supplemental fans (such as70FIG. 1) may dispose of this airstream 69 in any suitable manner-as bydissipating it into the atmosphere for example.

While the principles of the invention have been described above inconnection with specific apparatus and applications, it is to beunderstood that this description is made only by Way of example and notas a limitation on the scope of the invention.

We claim:

1. A rooftop air conditioner unit housing comprising an open area withinthe housing, said area having louvers on at least two sides, a pluralityof bafiles disposed 'adjacent to and below said louvers, said louverscomprising a plurality of slats having spaced parallel orientation forsplitting an incoming stream of air into a plurality of separateairstreams, each of-said slats having a generally L-shaped cross-sectionand a serif bend at the toe-end tip of the L-shaped cross-section, saidslats being positioned with respect to said airstreams so that the serifbend intercepts heavy particles in the airstream and deflects saidparticles toward said baffles, said separate airstreams then beingcombined and flowing into the air conditioning unit free from said heavyparticles.

2. A rooftop air conditioner according to claim 1 wherein the slats ofeach said louver are disposed vertically and said baffles comprise aslanted floor below said slats for draining away water which isintercepted by said serif bend.

References Cited UNITED STATES PATENTS 532,452 1/1895 Elwell 98371,896,656 2/1933 Anderson 2,737,876 3/1956 Smith 9842 3,348,466 10/1967Lane et al. 98121 3,358,580 12/1967 Freese et al. 98121 3,413,90512/1968 Johnson 9837 WILLIAM E. WAYNER, Primary Examiner US. Cl. X.R.-443; 98121

